The sample was racially and ethnically diverse and, overall, well educated (See ). The mean age of the sample was 23.9 (SD = 2.75, Range 18-29). There were no gender or sexual orientation differences in racial or ethnic diversity, employment status, or status as a student. Gay and bisexual men (M = 24.6) were older than heterosexual women (M = 23.5), F (3, 396) = 3.09, p < .05, and were the most likely to report making over $30K in the last year (49.5%, versus 38% among lesbian and bisexual women, 27% among heterosexual men, and 30% among heterosexual women; χ2  = 14.1, p < .05). Finally, gay and bisexual men were the most likely to report being single (78%), compared to lesbian and bisexual women (54%), heterosexual men (54%), and women (59%), χ2 (3) = 16.4, p < .001. There were no other demographic differences across the four groups.
Cocaine (94.5%, n
= 378) was the most common club drug ever used by participants and the most common drug used in the last 4 months (90.2%, n
=361). Ecstasy was second (87.8%, n
=351 ever; 53.5%, n
= 214 recent), followed by LSD (59.3%, n
= 237 ever; 19.5% n
= 78 recent), ketamine (51.5%, n
= 206 ever; 20%, n
= 80 recent), methamphetamine (42.3%, n
= 169 ever; 16.8%, n
= 67 recent); and GHB (21.5%, n
= 86 ever; 5.0%, n
= 20 recent). More information on the global patterns and prevalence of club drug use has been reported elsewhere (Parsons et al., in press-a
Participants also reported a range of other substances they had ever used, including alcohol (100%, n
= 400), marijuana (99%, n
=396), Psyloclibin/mushrooms (76%, n
= 304), heroin (15.8%, n
= 63), and a variety of non-prescribed prescription drugs including pain killers (e.g., Vicodin, Codine; 79.8%, n
= 319), sedatives (e.g., Valium, Xanax; 64.8%, n
= 259), stimulants (e.g., Ritalin, Adderall; 60.8%, n
= 243), and erectile dysfunction drugs (e.g., Viagra, Cialis, Levitra; 11.3%, n
= 45). More information on prescription drug abuse from this sample has been reported elsewhere.(Kelly & Parsons, 2007
As we could not anticipate the complete range of different polydrug combinations that participants would report, participants were specifically probed around their polydrug use while using each of the six club drugs and provided an opportunity to type (using a keyboard) polydrug combinations directly into ACASI. Nearly all participants (91.7%, n = 367) had combined drugs at one point in their lives. The prevalence of polydrug use closely mirrored the prevalence of club drug use such that polydrug use was highest for ecstasy (86.6% of ecstasy users had combined ecstasy with another drug), followed by cocaine (85.7%), ketamine (71.4%), LSD (69.2%), methamphetamine (66.3%), and GHB (54.7%). Values are reported in . In contrasting reported polydrug use by gender and sexual orientation, there were no significant differences in polydrug use of ecstasy, ketamine, GHB, methamphetamine, or cocaine. Heterosexual men were the most likely to have used LSD with another substance, χ2 (3) = 11.87, p < .01 (see ).
Gender and sexual orientation differences in polydrug usea
Among the 400 participants, with the six different club drugs, a total of 1,098 affirmative responses (e.g., combined [club drug name] with another drug? -- “yes”) were received. From these 1,098 affirmative responses, the follow up question resulted in participants having qualitatively typed a total of 1,670 drug responses into ACASI. These 1,670 responses were collapsed into meaningful categories (e.g., responses such as THC, pot, or weed were coded “marijuana”) and are reported in . In addition to combining club drugs with other club drugs, participants also indicated having combined club drugs with alcohol, marijuana, Psylocibin/mushrooms, and various prescription drugs used non-medically.
The most frequent polydrug combinations were reported for ecstasy (n = 681) and cocaine (n = 677), followed by LSD (n = 309), ketamine (n = 259), methamphetamine (n = 229), and GHB (n = 80). Not only were cocaine and ecstasy the most common drugs ever used, and the most common drugs used in conjunction with another drug, they also resulted in the largest number of possible drug combinations. In terms of polydrug combinations specifically with other club drugs, ecstasy was the most frequently endorsed drug (i.e., a universal compliment). For example, 351 participants reported ecstasy use and 206 participants reported ketamine use. Meanwhile, 198 participants reported having used both at one point in their lives (though not necessarily at the same time). Out of these 198 participants who had previously used ecstasy and ketamine at one point in their lives, 41.4% (n = 82) had specifically combined the two drugs. In addition, 37.4% (n = 125 of 334) of participants who had used ecstasy and cocaine had at one point combined the two, and 34.6% (28 of 81) of individuals having previously used ecstasy and GHB had at one point combined the two. Excluding ecstasy, other poly-club-drug combinations (i.e., club drugs with club drugs) were less common or non-existent (e.g., no participants combined GHB with LSD).
In terms of polydrug combinations between club drugs and other drugs, the four most common drug combinations were cocaine and marijuana (n = 226, 60.3% of cocaine and marijuana users had combined both), ecstasy and marijuana (n = 177, 50.6% of ecstasy and marijuana users had combined both), LSD and marijuana (n = 117, 49.4% of LSD and marijuana users had combined both), and cocaine and alcohol (n = 153, 40.5% of cocaine users). All other combinations are provided in .